One exemplary embodiment of the invention relates to a method for producing bound books, magazines or brochures by gathering printed signatures into unbound book blocks along a conveying section that is supplied by at least one sheet feeder, wherein the printed signatures or sheets are respectively lifted up along one edge region at the front of the printed sheet stack and are then withdrawn from the stack by means of a conveying element. Another exemplary embodiment of the invention also relates to an apparatus for producing bound books, magazines, or brochures by gathering printed signatures along a conveying section, the apparatus comprising a conveyor provided with carriers and at least one feeder, arranged above the conveyor, which supplies the latter with printed signatures or sheets removed from a stack front. The feeder in turn is provided with a separating device, which lifts up an exposed edge region of the printed signature or sheet on the front of the stack, as well as a conveying element that pulls the printed signature or sheet off at the stack front.
Swiss patent document CH 692 700 A5 discloses a gathering and collating machine provided with a series of feeding stations, which respectively comprise a magazine for receiving a stack of printed sheets and a device for separating the respectively lowest printed sheet. The gathering and collating machine furthermore comprises a gathering conveyor with driven carriers in a gathering channel to which the separated printed sheets are supplied for the stack formation. For one embodiment according to CH 692 700 A5, the stack of printed sheets is positioned above the gathering channel on a conveyor belt, provided with suction openings, wherein one side region with fold is left exposed in the printed sheet-conveying direction. The underside of the printed sheet is advanced far enough with the suction belt, so that it can be transported further by a subsequently installed withdrawing conveyor. Compressed air can be supplied via the lowest printed sheet that is slanted toward the side by means of the suction element for reducing the friction between the printed sheet to be pulled off and the one positioned above. A so-called pass-through guide is provided at the magazine discharge opening, which can be used to form an adjustable pass-through gap above the conveyor belt, so that respectively only the lowest printed sheet with fold is pulled from the stack.
This known separating device can be used for feeding sheets in longitudinal as well as transverse direction to the gathering channel.
One disadvantage of this separating device, however, is that the pass-through gap on the magazine discharge opening must be adjusted for holding back the subsequently arriving sheet. This operation results in considerable expenditure not only for thin printed sheets with folds, but for small format printed sheets with folds as oftentimes the small format printed sheets with folds do not have a large enough area of contact with the conveying belt, thus making a reliable separation impossible.